311. PROGNOSTIC VALUE OF DIFFERENT CIRCUMFERENTIAL MARGIN SITES IN OESOPHAGEAL CANCER: A 10-YEAR COHORT STUDY

Abstract Background There’s a growing interest towards the prognostic value of circumferential resection margin (CRM) involvement in oesophageal cancers. However, there is no sufficient data about the association of the site-specific CRM and survival. In this study, we analysed the influence of different involved CRM sites on survival. Methods This study included patients who had curative oesophagectomy for oesophageal cancer between 2010 till June 2021. Follow up till April 2022 was achieved. Patients with involved proximal or distal margins were excluded. The sites of CRM were defined anatomically to anterior (pericardial), posterior (aorta), lateral (pleurae). The outcomes between different CRM margins were retrospectively analysed. The long-term follow up data was obtained via direct contact with the patients during our oncological clinics, cross-checked with our hospital/national patients’ electronic databases. Results 117 patients had CRM-positive after curative oesophagectomy during the study period. 33 cases had multi-involved CRM sites, while 84 patients had single involved CRM site. Posterior margins were the most common involved site 37/117 (31.6%). No differences in baseline pathological criteria (pT, pN stages and type of cancer) and neoadjuvant therapy. Positive anterior margins carried the worst overall (OS) and disease-free (DFS) survival compared to lateral and posterior margins (OS: 29 vs 41 vs 32 months respectively, p-value 0.37, DFS: 19.2 vs 32.1 vs 28.7 months respectively, p-value 0.39). Multi-involved CRM sites led to worse OS and DFS in comparison with single involved CRM site (OS: 19 vs 32 months respectively, p-value 0.008, DFS: 12.1 months vs 27.6 months respectively, p-value 0.05). Conclusion The site of involved CRM should be rigorously assessed in oesophagectomy specimens. The involved margin sites within CRM had different survival rates, with inferiority towards anterior resection margins. Larger studies are required to better evaluate the prognostic significance of various CRM sites.